Numerical Simulation of Pressure Fluctuation around the Tongue Region in a Centrifugal Pump

Pressure fluctuation near the tongue is one of the primary sources of pump vibration and noise. In order to investigate the effect of pressure fluctuation near the tongue, the RANS equations and the RNG k-epsilon turbulence model are employed to simulate the flow in the pump. The SIMPLE algorithm is applied to couple the solutions of the system of equations. Flow field within the centrifugal pump under different flow rates are obtained by simulation. The simulation results are compared with the experimental data to verify the reliability of the calculation model. It is found that the pressure fluctuation at each monitor point is a periodic wave but non-uniform under small flow rate. When the flow rate is larger than the design flow rate, average pressure and standard deviation at monitor points is relative uniform. The dominate frequency of pressure fluctuation is the blade passing frequency and the amplitude of pressure fluctuation is regular. At small flow rate, complex unstable flow makes average pressure and standard deviation at monitor points increasing obviously. Amplitude of pressure fluctuation is larger than that of design flow rate conditions and the maximum amplitude of pressure fluctuation in frequency domain exists at the monitor point just behind the tongue along the impeller rotation direction.